Several recent developments in the art of remote elevator monitoring have provided increased monitoring capabilities for maintenance and planning purposes.
For example, U.S. Pat. No. 4,568,909, entitled "Remote Elevator Monitoring System" invented by Whynacht, discloses an elevator monitor for installation in a remote building. A plurality of discrete elevator parameter signals are continually monitored in order to enable the detection of various elevator system malfunctions as defined by a plurality of Boolean expressions which, when satisfied, trigger a message signal for initiating transmission thereof to a centrally located service office.
Another approach to elevator monitoring is disclosed in U.S. Pat. No. 4,622,538 issued to Whynacht et al. In that patent, the elevator system is conceived as a system which normally operates sequentially from state to state in a closed loop chain of linked normal operating states. A plurality of two-state parameter signals are monitored and, upon assuming a particular one of the states in the closed loop chain of events, a corresponding set of parameters are monitored to determine a transition from that state to the next expected state, and so on. Transitions from a normal operating state to abnormal states are detected and transitions back to normal are also tracked. The closed loop chain model proves particularly effective in monitoring in general and in making sure that all abnormal states are detected.
Although both approaches can certainly be embodied within the controller, both have heretofore been only embodied in separate hardware made especially for the monitoring function and mounted separately from the elevator controller which is normally mounted in the elevator car itself. Owing to the separateness of the monitoring hardware these approaches have been somewhat limited in the availability of some of the more useful parameter signals which are indicative of elevator conditions.